The dental calculus on the lower jaw where a medieval woman entrapped lapis lazuli pigment, seen below centre tooth. The find corroborates other findings that suggest female artisans in that time period were not as rare as previously thought.Christina Warinner/Max Planck Institute for the Science of Human History via AP)

The accidental discovery of microscopic crystals of a rare and precious Middle Eastern gemstone embedded in the tooth of an 11th-century German nun has cast a new light on the role of women in painting medieval religious texts, a field traditionally thought to have been dominated by male monks.

The most likely explanation, according to a new scientific paper, is that this woman was a painter using an exquisite blue pigment, which got into her mouth as she used her lips to twist her brush into a fine point.

“It almost looked like robin’s eggs,” said Christina Warinner of the department of archeogenetics at the Max Planck Institute for the Science of Human History. She was recalling the discovery of the blue flecks in the tooth with a colleague while both were studying other aspects of the remains such as diet and disease. The teeth are part of a set of 150 or so skeletons, male and female, excavated in 1989 during renovations to a medieval monastery in Germany, which was for men most of its history, but was originally a women’s commune between about AD 1000 and 1200, likely populated with wealthy, educated, literate, religious women.

It later suffered two instances of plague and the effects of battles, leading to a catastrophic fire and dispersal, even murder, of the women.

A magnified view of lapis lazuli particles embedded within the dental calculus of a medieval woman.Monica Tromp

After consulting with a physicist, Warinner learned that the flecks contained two minerals that are only present together in lapis lazuli, a gemstone mined only in a part of northern Afghanistan, and a classic example of a luxury good in medieval Europe and Asia. It was prized for its rich blue colour, and would often be processed into a pigment called ultramarine, which was used in lavish gospels and prayer books produced by hand in European monasteries.

The lapis lazuli crystals were preserved in this woman’s dental plaque, a “sticky bacterial biofilm” that builds up on teeth and can trap particles of whatever is in the mouth, from food starch to plant pollen. If it is not removed as in modern dentistry, it will calcify into a plaque, the only part of the human body that literally fossilizes during life, said Warinner.

An alternative theory to painting is that she was not involved in producing the manuscripts, but rather that she “performed emotive devotional osculation of illuminated books produced by others,” according to the new paper by Warinner and colleagues. In other words, she might have kissed the books, although this theory is less well supported, the authors conclude.

Only scribes and painters of exceptional skill would have been entrusted with its use

How lapis lazuli got to a religious community in northwest Europe is a story of commerce and empire, likely involving Near Eastern gemstone traders, pigment-makers in a major centre such as Alexandria in Egypt, and Venetian traders who dispersed ultramarine dye throughout Europe.

This nun, whoever she was, “was plugged into a vast global commercial network stretching from the mines of Afghanistan to her community in medieval Germany through the trading metropolises of Islamic Egypt and Byzantine Constantinople. The growing economy of 11th-century Europe fired demand for the precious and exquisite pigment that travelled thousands of miles via merchant caravan and ships to serve this woman artist’s creative ambition,” said co-author Michael McCormick of Harvard University.

A study of the nun’s skeletal remains shows she was about 45 to 60 years old when she died, with no obvious trauma or signs of disease.

A page from a Beatus Manuscript circa 1180.Metropolitan Museum of Art via AP

Warinner said a study of the social context of medieval German convents suggests the woman was likely at what the anthropologist called the “upper end of the social scale,” from a family that could afford to send her to such a community.

She was also likely a painter of some skill and authority, to be entrusted with such valuable materials, which would typically be provided by whoever had commissioned the religious text that was being painted.

“Within the context of medieval art, the application of highly pure ultramarine in illuminated works was restricted to luxury books of high value and importance, and only scribes and painters of exceptional skill would have been entrusted with its use,” reads the new paper in the journal Science Advances.